Semiconductor device and method for fabricating the same

ABSTRACT

The semiconductor device of the invention includes a capacitor device, which is formed on a substrate and which includes a capacitive lower electrode, a capacitive insulating film made of an insulating metal oxide film and a capacitive upper electrode. An interlevel insulating film having an opening reaching the capacitive upper electrode is formed over the capacitor device. A metal interconnection including a titanium film is formed over the interlevel insulating film so as to be electrically connected to the capacitive upper electrode through the opening. An anti-diffusion film having conductivity is formed between the capacitive upper electrode and the metal interconnection for preventing titanium atoms composing the titanium film of the metal interconnection from passing through the capacitive upper electrode and diffusing into the capacitive insulating film.

This application is a Divisional of application Ser. No. 09/120,893filed Jul. 23, 1998 now U.S. Pat. No. 6,239,462.

BACKGROUND OF THE INVENTION

The present invention generally relates to a semiconductor device and amethod for fabricating the same. More particularly, the presentinvention relates to a semiconductor device including a capacitor devicehaving a capacitive insulating film of insulating metal oxide film suchas a ferroelectric film or a high dielectric film (i.e., a film made ofa material having a high dielectric constant) and to a method forfabricating the same.

In recent years, as various electronic units such as microcomputersoperating at an even higher speed and with even lower power consumptionhave been developed, the performance of consumer-use electronic unitshave also been further enhanced. Correspondingly, the sizes ofsemiconductor devices used for these units have also been rapidlyreduced drastically.

As semiconductor devices have been miniaturized, unwanted radiation,i.e., electromagnetic wave noise generated from electronic units, hasbecome a serious problem. Technology for incorporating a large-capacitycapacitor device, including a ferroelectric film or a high dielectricfilm as a capacitive insulating film, into a semiconductor integratedcircuit is now the object of much attention as a means for reducing theunwanted radiation.

On the other hand, since a very highly integrated dynamic RAM is nowprovided, researches have been widely carried out on technology forusing a high dielectric film as a capacitive insulating film, instead ofa silicon oxide film or a silicon nitride film, which has beenconventionally used.

Furthermore, in order to put into practical use a non-volatile RAMoperating with a low voltage and enabling high-speed write and readoperations, researches and developments have also been vigorouslycarried out on a ferroelectric film having spontaneous polarizationproperties. A ferroelectric memory using a ferroelectric film as acapacitive insulating film takes advantage of a phenomenon that theamount of charge flowing into/out of a data line of a ferroelectricmemory differs depending upon whether or not the spontaneouspolarization of the ferroelectric film is inverted.

In all of these types of semiconductor devices mentioned above, it is anurgent task to develop technology for realizing very high integrationfor a capacitor device without deteriorating the characteristicsthereof.

Hereinafter, a conventional semiconductor device will be described withreference to FIG. 13.

FIG. 13 illustrates a cross-sectional structure of a conventionalsemiconductor device. As shown in FIG. 13, a lower electrode 2 made of afirst platinum film, a capacitive insulating film 3 made of aferroelectric film and an upper electrode 4 made of a second platinumfilm are formed in this order on a semiconductor substrate 1 made ofsilicon. The lower electrode 2, the capacitive insulating film 3 and theupper electrode 4 constitute a capacitor device. An interlevelinsulating film 5 made of a silicon oxide film, a silicon nitride filmor the like is deposited to cover the entire surface of thesemiconductor substrate 1 as well as the capacitor device. Alower-electrode contact hole 6 and an upper-electrode contact hole 7 areformed through the interlevel insulating film 5. Metal interconnections8, each consisting of a titanium film 8 a, a first titanium nitride film8 b, an aluminum film 8 c and a second titanium nitride film 8 d, areformed to cover the interlevel insulating film 5 as well as the innersurfaces of the lower-electrode contact hole 6 and the upper-electrodecontact hole 7.

Hereinafter, a method for fabricating the conventional semiconductordevice will be described with reference to FIGS. 14(a) through 14(e).

First, as shown in FIG. 14(a), the first platinum film 2A, theferroelectric film 3A and the second platinum film 4A are sequentiallystacked over the entire surface of the semi-conductor substrate 1.Thereafter, as shown in FIG. 14(b), the second platinum film 4A isselectively etched, thereby forming the upper electrode 4. Then, inorder to recover and stabilize the crystal structure of theferroelectric film 3A, the ferroelectric film 3A is subjected to a heattreatment within oxygen ambient.

Next, as shown in FIG. 14(c), the ferroelectric film 3A and the firstplatinum film 2A are selectively etched, thereby forming the capacitiveinsulating film 3 out of the ferroelectric film 3A and the lowerelectrode 2 out of the first platinum film 2A. Then, in order to recoverand stabilize the crystal structure of the ferroelectric filmconstituting the capacitive insulating film 3, the capacitive insulatingfilm 3 is subjected to a heat treatment within oxygen ambient.

Subsequently, as shown in FIG. 14(d), the interlevel insulating film 5made of a silicon oxide film or a silicon nitride film is deposited overthe entire surface of the semi-conductor substrate 1. And thelower-electrode contact hole 6 and the upper-electrode contact hole 7are formed through the interlevel insulating film 5. Then, in order torecover and stabilize the crystal structure of the ferroelectric filmconstituting the capacitive insulating film 3, the capacitive insulatingfilm 3 is subjected to a heat treatment within oxygen ambient.

In order to prevent the lower electrode 2 or the upper electrode 4 frombeing oxidized as a result of the reaction between the lower electrode 2or the upper electrode 4 with the capacitive insulating film 3 duringthe heat treatment conducted to recover and stabilize the crystalstructure of the ferroelectric film, the lower and the upper electrodes2, 4 are made of platinum, which is hard to react with the ferroelectricfilm 3A constituting the capacitive insulating film 3 during the heattreatment and exhibits anti-oxidation properties even at a hightemperature.

Then, as shown in FIG. 14(e), the titanium film 8 a, the first titaniumnitride film 8 b, the aluminum film 8 c and the second titanium nitridefilm 8 d are sequentially deposited to cover the entire surface of thesemiconductor substrate 1 as well as the inner surfaces of thelower-electrode contact hole 6 and the upper-electrode contact hole 7,thereby forming the metal interconnections 8, each consisting of thetitanium film 8 a, the first titanium nitride film 8 b, the aluminumfilm 8 c and the second titanium nitride film 8 d. The titanium film 8 afunctions as an adhesive film for improving the adhesion between thealuminum film 8 c and the platinum film constituting the upper electrode4. The first titanium nitride film 8 b functions as a barrier film forpreventing aluminum in the aluminum film 8 c from diffusing into thecapacitive insulating film 3. The second titanium nitride film 8 dfunctions as an anti-reflection film while an upper interlevelinsulating film deposited over the metal interconnections 8 is etched.

Next, in order to further improve the adhesion between the titanium film8 a constituting the metal interconnections 8 and the interlevelinsulating film 5, the metal interconnections 8 are subjected to a heattreatment.

However, during the heat treatment conducted to stabilize the crystalstructure of the ferroelectric film, the platinum film constituting theupper electrode comes to have column like crystal structure. Thus,during the heat treatment conducted to improve the adhesion between themetal interconnections and the interlevel insulating film, the titaniumatoms in the titanium film constituting the metal interconnectionsadversely pass through the grain boundary of the column like crystals ofthe platinum film constituting the upper electrode so as to diffuse intothe capacitive insulating film. As a result, since the composition ofthe ferroelectric film or the high dielectric film constituting thecapacitive insulating film is varied, the electrical characteristics ofthe capacitor device are disadvantageously deteriorated.

It is not only when the upper electrode is made of platinum but alsowhen the upper electrode is made of iridium, ruthenium, rhodium,palladium or the like that the upper electrode ordinarily has a columnlike crystal structure. Thus, in the latter case, the titanium atoms inthe titanium film constituting the metal interconnections also adverselypass through the grain boundary of the column like crystals constitutingthe upper electrode so as to diffuse into the capacitive insulatingfilm.

SUMMARY OF THE INVENTION

In view of the foregoing, the object of the present invention is toprevent titanium atoms in a titanium film from passing through the grainboundary of metal crystals composing the upper electrode of a capacitordevice and diffusing into a capacitive insulating film during a heattreatment conducted on metal interconnections, which are formed on thecapacitor device and include the titanium film.

In order to accomplish the object, the semiconductor device according tothe present invention includes: a substrate; a capacitor device, whichis formed on the substrate and includes a capacitive lower electrode, acapacitive insulating film made of an insulating metal oxide film and acapacitive upper electrode; an interlevel insulating film, which isformed on the capacitor device and has an opening reaching thecapacitive upper electrode; a metal interconnection, which is formed onthe interlevel insulating film so as to be electrically connected to thecapacitive upper electrode through the opening and includes a titaniumfilm; and an anti-diffusion film, which is formed between the capacitiveupper electrode and the metal interconnection, has conductivity andprevents titanium atoms composing the titanium film of the metalinterconnection from passing through the capacitive upper electrode anddiffusing into the capacitive insulating film.

In the semiconductor device of the present invention, an anti-diffusionfilm for preventing titanium atoms composing the titanium film of themetal interconnection from passing through the capacitive upperelectrode and diffusing into the capacitive insulating film is formedbetween the capacitive upper electrode and the metal interconnection.Thus, during the heat treatment on the metal interconnection, thetitanium atoms in the titanium film do not pass through the grainboundary of metal crystals composing the capacitive upper electrode anddo not diffuse into the capacitive insulating film. Accordingly, asemiconductor device including a highly reliable capacitor device can beformed.

In the semiconductor device of the present invention, the anti-diffusionfilm is preferably a metal nitride film or metal oxide film havingconductivity.

In such an embodiment, since the conductive metal nitride film or metaloxide film has no grain boundary and has a dense structure, the film canprevent the passage of titanium atoms with certainty. In particular, ifthe anti-diffusion film is a conductive metal oxide film, theconductivity of the film is not damaged even when a heat treatment isconducted within oxygen ambient in order to recover the crystalstructure of the ferroelectric film constituting the capacitiveinsulating film. This is because the metal oxide film has conductivityin the state of an oxide.

In the semiconductor device of the present invention, if the capacitiveinsulating film is a ferroelectric film, a highly reliable nonvolatilememory can be obtained. On the other hand, if the capacitive insulatingfilm is a high dielectric film, a highly reliable dynamic memory can beobtained.

In the semiconductor device of the present invention, the titanium filmis preferably an adhesive layer, formed as a lowermost layer of themetal interconnection, for improving adhesion between the metalinterconnection and the upper electrode, and the anti-diffusion film ispreferably a titanium nitride film.

In such an embodiment, since the titanium film is an adhesive layer, theadhesion between the metal interconnection and the upper electrode canbe improved. In addition, if the anti-diffusion film is a titaniumnitride film, then no by-product is formed during the deposition of theanti-diffusion film. Moreover, even if titanium in the titanium filmdiffuses toward the anti-diffusion film over a certain distance, thenature of the anti-diffusion film is not changed and the characteristicsof the capacitor device are stabilized.

In the semiconductor device of the present invention, the capacitiveupper electrode preferably has a crystal structure including a grainboundary.

In such an embodiment, although the titanium atoms are more likely topass through the capacitive upper electrode, the titanium atoms do notdiffuse into the capacitive insulating film because the atoms areprevented by the anti-diffusion film from reaching the capacitive upperelectrode.

A first method for fabricating a semiconductor device according to thepresent invention includes the steps of: forming a capacitor device,including a capacitive lower electrode, a capacitive insulating filmmade of an insulating metal oxide film and a capacitive upper electrode,on a substrate; forming an interlevel insulating film, having a contacthole reaching the capacitive upper electrode, on the capacitor device;depositing a conductive film, preventing the passage of titanium atomstherethrough, so as to cover the entire surface of the interlevelinsulating film as well as the contact hole; patterning the conductivefilm such that at least a part of the conductive film located inside thecontact hole is left, thereby forming an anti-diffusion film out of theconductive film; and forming, on the interlevel insulating film, a metalinterconnection including a titanium film such that the metalinterconnection is electrically connected to the capacitive upperelectrode via the anti-diffusion film.

In the first method for fabricating a semiconductor device, a conductivefilm, preventing the passage of titanium atoms, is deposited over aninterlevel insulating film formed on the capacitor device and includinga contact hole. Then, the conductive film is patterned, thereby leavingthe part of the conductive film located inside the contact hole. Thus,the anti-diffusion film for preventing the titanium atoms from passingthrough the capacitive upper electrode and diffusing into the capacitiveinsulating film can be formed between the upper electrode of thecapacitor device and the metal inter-connection with certainty.

A second method for fabricating a semiconductor device according to thepresent invention, includes the steps of: forming a capacitor device,including a capacitive lower electrode, a capacitive insulating filmmade of an insulating metal oxide film and a capacitive upper electrode,on a substrate; forming an interlevel insulating film, having a contacthole reaching the capacitive upper electrode, on the capacitor device;forming, on the interlevel insulating film, a resist pattern having anopening at a site corresponding to the contact hole; depositing aconductive film, preventing the passage of titanium atoms therethrough,so as to cover the entire surface of the resist pattern; lifting off theconductive film together with the resist pattern such that a part of theconductive film located inside the contact hole is left, thereby formingan anti-diffusion film out of the conductive film; and forming, on theinterlevel insulating film, a metal interconnection including a titaniumfilm such that the metal interconnection is electrically connected tothe capacitive upper electrode via the anti-diffusion film.

In the second method for fabricating a semiconductor device, a resistpattern having an opening at a site corresponding to a contact hole isformed on the interlevel insulating film formed on the capacitor deviceand including the contact hole, and a conductive film, preventing thepassage of titanium atoms therethrough, is deposited thereon. Thus, theanti-diffusion film for preventing the titanium atoms from passingthrough the capacitive upper electrode and diffusing into the capacitiveinsulating film can be formed between the upper electrode of thecapacitor device and the metal interconnection with certainty.

A third method for fabricating a semiconductor device according to thepresent invention includes the steps of: sequentially stacking a firstmetal film, an insulating metal oxide film, a second metal film and aconductive film, preventing the passage of titanium atoms therethrough,on a substrate; patterning the second metal film and the conductive filmby using the same etching mask, thereby forming a capacitive upperelectrode out of the second metal film and an anti-diffusion film out ofthe conductive film; patterning the insulating metal oxide film to forma capacitive insulating film and patterning the first metal film to forma capacitive lower electrode; forming an interlevel insulating film,having a contact hole reaching the capacitive upper electrode, over acapacitor device constituted by the capacitive lower electrode, thecapacitive insulating film and the capacitive upper electrode; andforming, on the interlevel insulating film, a metal interconnectionincluding a titanium film such that the metal interconnection iselectrically connected to the capacitive upper electrode via theanti-diffusion film.

In the third method for fabricating a semiconductor device, among thesequentially stacked first metal film, insulating metal oxide film,second metal film and conductive film preventing the passage of titaniumatoms therethrough, the second metal film and the conductive film arepatterned first, thereby forming a capacitive upper electrode and ananti-diffusion film. Then, a metal interconnection including a titaniumfilm is formed over the interlevel insulating film having a contacthole. Thus, the anti-diffusion film for preventing the titanium atomsfrom passing through the capacitive upper electrode and diffusing intothe capacitive insulating film can be formed between the upper electrodeof the capacitor device and the metal interconnection with certainty.

A fourth method for fabricating a semiconductor device according to thepresent invention includes the steps of: forming a capacitive lowerelectrode and a capacitive insulating film made of an insulating metaloxide film on a substrate; depositing an interlevel insulating film soas to cover the substrate as well as the capacitive insulating film;forming a resist pattern over the interlevel insulating film, the resistpattern having an opening over a region where a capacitive upperelectrode is to be formed; etching the interlevel insulating film byusing the resist pattern as a mask, thereby forming an upper electrodeforming opening through the interlevel insulating film; sequentiallydepositing a metal film and a conductive film preventing the passage oftitanium atoms therethrough so as to cover the entire surface of theresist pattern as well as the upper electrode forming opening; liftingoff the metal film and the conductive film together with the resistpattern such that part of the metal film and part of the conductivefilm, which are located in the upper electrode forming opening, areleft, thereby forming the capacitive upper electrode out of the metalfilm and an anti-diffusion film out of the conductive film; and forming,on the interlevel insulating film, a metal interconnection including atitanium film such that the metal interconnection is electricallyconnected to the capacitive upper electrode via the anti-diffusion film.

In the fourth method for fabricating a semiconductor device, theinterlevel insulating film is etched by using, as a mask, a resistpattern including an opening over the region where the capacitive upperelectrode is to be formed, thereby forming an upper electrode formingopening through the interlevel insulating film. Then, a metal film and aconductive film preventing the passage of titanium atoms therethroughare deposited, and a metal interconnection including a titanium film isformed thereon. Thus, the anti-diffusion film for preventing thetitanium atoms from passing through the capacitive upper electrode anddiffusing into the capacitive insulating film can be formed between theupper electrode of the capacitor device and the metal interconnectionwith certainty.

Therefore, in accordance with the first to fourth methods forfabricating a semiconductor device, the semiconductor device of thepresent invention can be fabricated with certainty.

In the first to fourth methods for fabricating a semiconductor device,the conductive film is preferably a metal nitride film or metal oxidefilm having conductivity.

In the first to fourth methods for fabricating a semiconductor device,the capacitive insulating film is preferably a ferroelectric film or ahigh dielectric film.

In the first to fourth methods for fabricating a semiconductor device,the titanium film is preferably an adhesive layer, formed as a lowermostlayer of the metal interconnection, for improving adhesion between themetal interconnection and the capacitive upper electrode, and theanti-diffusion film is preferably a titanium nitride film.

In the first to fourth methods for fabricating a semiconductor device,the capacitive upper electrode preferably has a crystal structureincluding a grain boundary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a semiconductor device in the firstembodiment of the present invention.

FIG. 2 is a cross-sectional view of a semiconductor device in the secondembodiment of the present invention.

FIG. 3 is a cross-sectional view of a semiconductor device in avariation of the second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a semiconductor device in the thirdembodiment of the present invention.

FIG. 5 is a cross-sectional view of a semiconductor device in the fourthembodiment of the present invention.

FIGS. 6(a) through 6(c) are cross-sectional views illustratingrespective process steps in a method for fabricating the semiconductordevice of the first embodiment of the present invention.

FIGS. 7(a) through 7(c) are cross-sectional views illustratingrespective process steps in the method for fabricating the semiconductordevice of the first embodiment of the present invention.

FIGS. 8(a) through 8(c) are cross-sectional views illustratingrespective process steps in a method for fabricating the semiconductordevice of the second embodiment of the present invention.

FIGS. 9(a) through 9(c) are cross-sectional views illustratingrespective process steps in the method for fabricating the semiconductordevice of the second embodiment of the present invention.

FIGS. 10(a) through 10(e) are cross-sectional views illustratingrespective process steps in a method for fabricating the semiconductordevice of the third embodiment of the present invention.

FIGS. 11(a) through 11(c) are cross-sectional views illustratingrespective process steps in a method for fabricating the semiconductordevice of the fourth embodiment of the present invention.

FIGS. 12(a) through 12(c) are cross-sectional views illustratingrespective process steps in the method for fabricating the semiconductordevice of the fourth embodiment of the present invention.

FIG. 13 is a cross-sectional view of a conventional semiconductordevice.

FIGS. 14(a) through 14(e) are cross-sectional views illustratingrespective process steps in a conventional method for fabricating asemiconductor device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment 1

Hereinafter, a semiconductor device according to the first embodiment ofthe present invention will be described with reference to FIG. 1.

FIG. 1 illustrates a cross-sectional structure of the semiconductordevice in the first embodiment. As shown in FIG. 1, a lower electrode 11made of a first platinum film, a capacitive insulating film 12 made ofan insulating metal oxide film such as a ferroelectric film or a highdielectric film, and an upper electrode 13 made of a second platinumfilm are sequentially formed on a semiconductor substrate 10 made ofsilicon. The lower electrode 11, the capacitive insulating film 12 andthe upper electrode 13 constitute a capacitor device. In thisembodiment, the size of the lower electrode 11 is larger than that ofthe upper electrode 13 such that a metal interconnection can be extendedupward to pass by the sides of the upper electrode 13 and beelectrically connected to the lower electrode 11.

An interlevel insulating film 14 made of a silicon oxide film, forexample, is deposited to cover the entire surface of the semiconductorsubstrate 10 as well as the capacitor device. A lower-electrode contacthole 15 and an upper-electrode contact hole 16 are formed through theinterlevel insulating film 14.

The first embodiment is characterized by including an anti-diffusionconductive film 17 made of a conductive metal nitride film (e.g., atitanium nitride film) on the inner bottom surface and inner wallsurfaces of the upper-electrode contact hole 16 and on a part of theinterlevel insulating film 14 surrounding the upper-electrode contacthole 16.

Metal interconnections 18, each consisting of a titanium film 18 a, afirst titanium nitride film 18 b, an aluminum film 18 c and a secondtitanium nitride film 18 d, are formed over the interlevel insulatingfilm 14 as well as the inner surfaces of the lower-electrode contacthole 15 and the upper-electrode contact hole 16. In this embodiment, oneof the metal interconnections 18 is electrically connected to the lowerelectrode 11 directly inside the lower-electrode contact hole 15. Theother metal interconnection 18 is electrically connected to the upperelectrode 13 via the anti-diffusion conductive film 17 inside theupper-electrode contact hole 16.

It is noted that the titanium film 18 a functions as an adhesive layerfor improving the adhesion between the aluminum film 18 c and the lowerelectrode 11 and between the aluminum film 18 c and the upper electrode13. The first titanium nitride film 18 b functions as a barrier layerfor preventing aluminum in the aluminum film 18 c from diffusing intothe capacitive insulating film 12. The second titanium nitride film 18 dfunctions as an anti-reflection film while an upper interlevelinsulating film to be deposited on the metal interconnections 18 isetched.

Hereinafter, a method for fabricating the semiconductor device in thefirst embodiment of the present invention will be described withreference to FIGS. 6(a) through 6(c) and FIGS. 7(a) through 7(c).

First, as shown in FIG. 6(a), the first platinum film 11A, theferroelectric film 12A and the second platinum film 13A are sequentiallystacked over the entire surface of the semiconductor substrate 10.

Thereafter, as shown in FIG. 6(b), the second platinum film 13A isselectively etched, thereby forming the upper electrode 13. Then, theferroelectric film 12A and the first platinum film 11A are selectivelyetched, thereby forming the capacitive insulating film 12 out of theferroelectric film 12A and the lower electrode 11 out of the firstplatinum film 11A. In this embodiment, the ferroelectric film 12A andthe first platinum film 11A are preferably etched by using the samemask, because mask misalignment can be prevented by doing so.Alternatively, the ferroelectric film 12A and the first platinum film11A may be etched separately by using respectively different masks.Then, the capacitive insulating film 12 is selectively etched in orderto form a region from which a metal interconnection to be electricallyconnected to the lower electrode 11 is extended upward. Subsequently, inorder to recover and stabilize the crystal structure of theferroelectric film constituting the capacitive insulating film 12, thecapacitive insulating film 12 is subjected to a heat treatment withinoxygen ambient.

Next, as shown in FIG. 6(c), the interlevel insulating film 14 made of asilicon oxide film is deposited over the entire surface of thesemiconductor substrate 10. And the interlevel insulating film 14 isselectively etched, thereby forming the lower-electrode contact hole 15and the upper-electrode contact hole 16. Then, in order to recover andstabilize the crystal structure of the ferroelectric film constitutingthe capacitive insulating film 12, the capacitive insulating film 12 issubjected to a heat treatment within oxygen ambient.

Next, as shown in FIG. 7(a), the titanium nitride film 17A is depositedso as to cover the entire surface of the semiconductor substrate 10 aswell as the inner surfaces of the lower-electrode contact hole 15 andthe upper-electrode contact hole 16. Then, a resist pattern 19 having anopening over the upper-electrode contact hole 16 and the surroundingregion thereof is formed over the titanium nitride film 17A.

Subsequently, as shown in FIG. 7(b), the titanium nitride film 17A isetched by using the resist pattern 19 as a mask, thereby forming theanti-diffusion conductive film 17 out of the titanium nitride film 17Aso as to cover the inner bottom surface and inner wall surfaces of theupper-electrode contact hole 16 and part of the upper surface of theinterlevel insulating film 14 surrounding the upper-electrode contacthole 16.

Then, as shown in FIG. 7(c), the metal interconnections 18, eachconsisting of the titanium film 18 a, the first titanium nitride film 18b, the aluminum film 18 c and the second titanium nitride film 18 d, areformed over the anti-diffusion conductive film 17 and the interlevelinsulating film 14. The titanium film 18 a functions as an adhesivelayer for improving the adhesion between the aluminum film 18 c and thelower electrode 11 and between the aluminum film 18 c and the upperelectrode 13. The first titanium nitride film 18 b functions as abarrier layer for preventing aluminum in the aluminum film 18 c fromdiffusing into the capacitive insulating film 12. The second titaniumnitride film 18 d functions as an anti-reflection film while an upperinterlevel insulating film to be deposited over the metalinterconnections 18 is etched.

Next, in order to further improve the adhesion between the titanium film18 a constituting the metal interconnections 18 and the interlevelinsulating film 14, the metal interconnections 18 are subjected to aheat treatment.

In the first embodiment, the inner bottom surface and inner wallsurfaces of the upper-electrode contact hole 16 and the part of theupper surface of the interlevel insulating film 14 surrounding theupper-electrode contact hole 16 are covered with the anti-diffusionconductive film 17 made of the titanium nitride film 17A including nograin boundaries and having a dense structure. Thus, the titanium atomsin the titanium film 18 a constituting the metal interconnections 18 donot pass through the anti-diffusion conductive film 17. Accordingly,during the heat treatment conducted on the metal interconnections 18, itis possible to prevent the titanium atoms in the titanium film 18 a frompassing through the grain boundaries of metal crystals composing theupper electrode 13 and diffusing into the capacitive insulating film 12.As a result, in the first embodiment, a semiconductor device including ahighly reliable capacitor device can be formed.

In addition, in the first embodiment, not only the inner surfaces of theupper-electrode contact hole 16 but also the part of the upper surfaceof the interlevel insulating film 14 surrounding the upper-electrodecontact hole 16 are covered with the anti-diffusion conductive film 17.Thus, even when a mask used for patterning the titanium nitride film 17Ais out of alignment to a certain degree, the inner bottom surface of theupper-electrode contact hole 16 can be covered with the anti-diffusionconductive film 17 with certainty.

Hereinafter, the evaluation of the semiconductor device of the firstembodiment will be described.

Table 1 shows in comparison the characteristics of the capacitor devicein the semiconductor device of the first embodiment and thecharacteristics of a capacitor device in a conventional semiconductordevice.

TABLE 1 Data retention time Breakdown voltage (V) (years) FirstEmbodiment 40 10 Conventional Capacitor 20 1

As can be understood from Table 1, in the first embodiment, thebreakdown voltage of the capacitor device is 40 V, which is twice ashigh as that of the conventional capacitor device. The data retentiontime of the capacitor device of the first embodiment is 10 years, whichis ten times as long as that of the conventional capacitor device.

Embodiment 2

Hereinafter, a semiconductor device according to the second embodimentof the present invention will be described with reference to FIG. 2.

FIG. 2 illustrates a cross-sectional structure of the semiconductordevice in the second embodiment. As shown in FIG. 2, a lower electrode21 made of a first platinum film, a capacitive insulating film 22 madeof an insulating metal oxide film such as a ferroelectric film or a highdielectric film, and an upper electrode 23 made of a second platinumfilm are sequentially formed on a semiconductor substrate 20 made ofsilicon. The lower electrode 21, the capacitive insulating film 22 andthe upper electrode 23 constitute a capacitor device.

An interlevel insulating film 24 made of a silicon oxide film, forexample, is deposited to cover the entire surface of the semiconductorsubstrate 20 as well as the capacitor device. A lower-electrode contacthole 25 and an upper-electrode contact hole 26 are formed through theinterlevel insulating film 24.

The second embodiment is characterized in that an anti-diffusionconductive film 27 made of a titanium nitride film is filled in theupper-electrode contact hole 26.

Metal interconnections 28, each consisting of a titanium film 28 a, afirst titanium nitride film 28 b, an aluminum film 28 c and a secondtitanium nitride film 28 d, are formed so as to cover the interlevelinsulating film 24 as well as the inner surfaces of the lower-electrodecontact hole 25. In this embodiment, one of the metal interconnections28 is electrically connected to the lower electrode 21 directly insidethe lower-electrode contact hole 25. The other metal interconnection 28is electrically connected to the upper electrode 23 via theanti-diffusion, conductive film 27 above the upper-electrode contacthole 26. In other words, the latter metal interconnection 28 iselectrically connected to the upper electrode 23 without being bent inthe vertical direction. Thus, the latter metal interconnection 28 can beelectrically connected to the upper electrode 23 with more certainty.

Hereinafter, a semiconductor device according to a variation of thesecond embodiment of the present invention will be described withreference to FIG. 3.

FIG. 3 illustrates a cross-sectional structure of the semiconductordevice in the variation of the second embodiment. Only the differencebetween the second embodiment and this variation will be describedbelow.

The variation of the second embodiment is characterized in that theanti-diffusion conductive film 27 made of a titanium nitride film, forexample, is deposited only in the lower part inside the upper-electrodecontact hole 26. Thus, part of the metal interconnection 28 consistingof the titanium film 28 a, the first titanium nitride film 28 b, thealuminum film 28 c and the second titanium nitride film 28 d is locatedinside the upper-electrode contact hole 26. Accordingly, one of themetal interconnections 28 is electrically connected to the lowerelectrode 21 directly inside the lower-electrode contact hole 25. Theother metal interconnection 28 is electrically connected to the upperelectrode 23 via the anti-diffusion conductive film 27 inside theupper-electrode contact hole 26.

Hereinafter, a method for fabricating the semiconductor device in thesecond embodiment of the present invention will be described withreference to FIGS. 8(a) through 8(c) and FIGS. 9(a) through 9(c).

First, as shown in FIG. 8(a), the first platinum film 21A, theferroelectric film 22A and the second platinum film 23A are sequentiallystacked over the entire surface of the semiconductor substrate 20.

Thereafter, as shown in FIG. 8(b), the second platinum film 23A isselectively etched, thereby forming the upper electrode 23. Then, theferroelectric film 22A and the first platinum film 21A are selectivelyetched, thereby forming the capacitive insulating film 22 out of theferroelectric film 22A and the lower electrode 21 out of the firstplatinum film 21A. Then, the capacitive insulating film 22 isselectively etched in order to form a region from which a metalinterconnection to be electrically connected to the lower electrode 21is extended upward. Subsequently, in order to recover and stabilize thecrystal structure of the ferroelectric film constituting the capacitiveinsulating film 22, the capacitive insulating film 22 is subjected to aheat treatment within oxygen ambient.

Next, as shown in FIG. 8(c), the interlevel insulating film 24 made of asilicon oxide film is deposited over the entire surface of thesemiconductor substrate 20. And the interlevel insulating film 24 isselectively etched, thereby forming the lower-electrode contact hole 25and the upper-electrode contact hole 26. Then, in order to recover andstabilize the crystal structure of the ferroelectric film constitutingthe capacitive insulating film 22, the capacitive insulating film 22 issubjected to a heat treatment within oxygen ambient.

Thereafter, a resist pattern 29 (not shown) having an opening in aregion corresponding to the upper-electrode contact hole 26 is formedover the interlevel insulating film 24 and the titanium nitride film 27Ais deposited over the entire surface of the semiconductor substrate 20.

Subsequently, the resist pattern (not shown) is removed and the titaniumnitride film 27A deposited on the resist pattern is lifted off, therebyforming the anti-diffusion conductive film 27 out of the titaniumnitride film 27A so as to fill in only the inside of the upper-electrodecontact holes 26 and 25. Next, as shown in FIG. 9(a), a second resistpattern 29 is formed on the titanium nitride film 27A in the openingcorresponding to the upper electrode contact hole 26. Next, as shown inFIG. 9(b), after removing the titanium nitride film 27A inside the lowerelectrode contact hole 25 and the second resist pattern 29, the titaniumnitride film 27A inside the upper electrode contact hole 26 is remained.

Then, as shown in FIG. 9(c), the metal interconnections 28, eachconsisting of the titanium film 28 a, the first titanium nitride film 28b, the aluminum film 28 c and the second titanium nitride film 28 d, areformed over the anti-diffusion conductive film 27 and the interlevelinsulating film 24. Next, in order to further improve the adhesionbetween the titanium film 28 a constituting the metal interconnections28 and the interlevel insulating film 24, the metal interconnections 28are subjected to a heat treatment.

In the second embodiment and the variation thereof, the anti-diffusionconductive film 27 made of the titanium nitride film 27A including nograin boundaries and having a dense structure is formed inside theupper-electrode contact hole 26. Thus, the titanium atoms in thetitanium film 28 a constituting the metal interconnections 28 do notpass through the anti-diffusion conductive film 27. Accordingly, duringthe heat treatment conducted on the metal interconnections 28, it ispossible to prevent the titanium atoms in the titanium film 28 a frompassing through the grain boundaries of metal crystals composing theupper electrode 23 and diffusing into the capacitive insulating film 22.As a result, in the second embodiment and the variation thereof, asemi-conductor device including a highly reliable capacitor device canbe formed.

In addition, in the second embodiment, since the anti-diffusionconductive film 27 is filled in the upper-electrode contact hole 26, themetal interconnection 28 is not bent over the upper-electrode contacthole 26. Thus, the contact between the metal interconnection 28 and theupper electrode 23 is satisfactory.

Hereinafter, the evaluation of the semiconductor device of the secondembodiment will be described.

Table 2 shows in comparison the characteristics of the capacitor devicein the semiconductor device of the second embodiment and thecharacteristics of a capacitor device in a conventional semiconductordevice.

TABLE 2 Data retention time Breakdown voltage (V) (years) SecondEmbodiment 40 10 Conventional Capacitor 20 1

As can be understood from Table 2, in the second embodiment, thebreakdown voltage of the capacitor device is 40 V, which is twice ashigh as that of the conventional capacitor device. The data retentiontime of the capacitor device of the second embodiment is 10 years, whichis ten times as long as that of the conventional capacitor device.

Embodiment 3

Hereinafter, a semiconductor device according to the third embodiment ofthe present invention will be described with reference to FIG. 4.

FIG. 4 illustrates a cross-sectional structure of the semiconductordevice in the third embodiment. As shown in FIG. 4, a lower electrode 31made of a first platinum film, a capacitive insulating film 32 made ofan insulating metal oxide film such as a ferroelectric film or a highdielectric film, and an upper electrode 33 made of a second platinumfilm are sequentially formed on a semiconductor substrate 30 made ofsilicon. The lower electrode 31, the capacitive insulating film 32 andthe upper electrode 33 constitute a capacitor device.

An interlevel insulating film 34 made of a silicon oxide film, a siliconnitride film or the like, is deposited to cover the entire surface ofthe semiconductor substrate 30 as well as the capacitor device. Alower-electrode contact hole 35 and an upper-electrode contact hole 36are formed through the interlevel insulating film 34.

The third embodiment is characterized in that an anti-diffusionconductive film 37 made of a titanium nitride film having the sameplanar shape as that of the upper electrode 33 is formed on the upperelectrode 33.

Metal interconnections 38, each consisting of a titanium film 38 a, afirst titanium nitride film 38 b, an aluminum film 38 c and a secondtitanium nitride film 38 d, are formed to cover the interlevelinsulating film 34 as well as the inner surfaces of the lower-electrodecontact hole 35 and the upper-electrode contact hole 36. In thisembodiment, one of the metal interconnections 38 is electricallyconnected to the lower electrode 31 directly inside the lower-electrodecontact hole 35. The other metal interconnection 38 is electricallyconnected to the upper electrode 33 at the bottom of the upper-electrodecontact hole 36 via the anti-diffusion conductive film 37.

Hereinafter, a method for fabricating the semiconductor device in thethird embodiment of the present invention will be described withreference to FIGS. 10(a) through 10(e).

First, as shown in FIG. 10(a), the first platinum film 31A, theferroelectric film 32A, the second platinum film 33A and the titaniumnitride film 37A are sequentially stacked over the entire surface of thesemiconductor substrate 30.

Thereafter, as shown in FIG. 10(b), the titanium nitride film 37A andthe second platinum film 33A are patterned by using the same etchingmask, thereby forming the anti-diffusion conductive film 37 out of thetitanium nitride film 37A and the upper electrode 33 out of the secondplatinum film 33A. Subsequently, in order to recover and stabilize thecrystal structure of the ferroelectric film 32A, the ferroelectric film32A is subjected to a heat treatment within oxygen ambient.

Then, as shown in FIG. 10(c), the ferroelectric film 32A and the firstplatinum film 31A are patterned, thereby forming the capacitiveinsulating film 32 out of the ferroelectric film 32A and the lowerelectrode 31 out of the first platinum film 31A. Thereafter, thecapacitive insulating film 32 is selectively etched in order to form aregion from which a metal interconnection to be electrically connectedto the lower electrode 31 is extended upward. Subsequently, in order torecover and stabilize the crystal structure of the ferroelectric filmconstituting the capacitive insulating film 32, the capacitiveinsulating film 32 is subjected to a heat treatment within oxygenambient.

Next, as shown in FIG. 10(d), the interlevel insulating film 34 made ofa silicon oxide film is deposited over the entire surface of thesemiconductor substrate 30. And the interlevel insulating film 34 isselectively etched, thereby forming the lower-electrode contact hole 35and the upper-electrode contact hole 36. Then, in order to recover andstabilize the crystal structure of the ferroelectric film constitutingthe capacitive insulating film 32, the capacitive insulating film 32 issubjected to a heat treatment within oxygen ambient.

Next, as shown in FIG. 10(e), the metal interconnections 38, eachconsisting of the titanium film 38 a, the first titanium nitride film 38b, the aluminum film 38 c and the second titanium nitride film 38 d, areformed over the anti-diffusion conductive film 37 and the interlevelinsulating film 34. Then, in order to further improve the adhesionbetween the titanium film 38 a constituting the metal interconnections38 and the interlevel insulating film 34, the metal interconnections 38are subjected to a heat treatment.

In the third embodiment, the anti-diffusion conductive film 37 made ofthe titanium nitride film 37A including no grain boundaries and having adense structure is formed under the bottom of the upper-electrodecontact hole 36. Thus, the titanium atoms in the titanium film 38 aconstituting the metal interconnection 38 do not pass through theanti-diffusion conductive film 37. Accordingly, during the heattreatment conducted on the metal interconnections 38, it is possible toprevent the titanium atoms in the titanium film 38 a from passingthrough the grain boundaries of metal crystals composing the upperelectrode 33 and diffusing into the capacitive insulating film 32. As aresult, in the third embodiment, a semiconductor device including ahighly reliable capacitor device can be formed.

Hereinafter, the evaluation of the semiconductor device of the thirdembodiment will be described.

Table 3 shows in comparison the characteristics of the capacitor devicein the semiconductor device of the third embodiment and thecharacteristics of a capacitor device in a conventional semiconductordevice.

TABLE 3 Data retention time Breakdown voltage (V) (years) ThirdEmbodiment 40 10 Conventional Capacitor 20 1

As can be understood from Table 3, in the third embodiment, thebreakdown voltage of the capacitor device is 40 V, which is twice ashigh as that of the conventional capacitor device. The data retentiontime of the capacitor device of the third embodiment is 10 years, whichis ten times as long as that of the conventional capacitor device.

Embodiment 4

Hereinafter, a semiconductor device according to the fourth embodimentof the present invention will be described with reference to FIG. 5.

FIG. 5 illustrates a cross-sectional structure of the semiconductordevice in the fourth embodiment. As shown in FIG. 5, a lower electrode41 made of a first platinum film, a capacitive insulating film 42 madeof an insulating metal oxide film such as a ferroelectric film or a highdielectric film, and an upper electrode 43 made of a second platinumfilm are sequentially formed on a semiconductor substrate 40 made ofsilicon. The lower electrode 41, the capacitive insulating film 42 andthe upper electrode 43 constitute a capacitor device.

An interlevel insulating film 44, made of a silicon oxide film, asilicon nitride film or the like, is deposited to cover the entiresurface of the semiconductor substrate 40 as well as the capacitordevice. A lower-electrode contact hole 45 and an upper-electrode contacthole 46 are formed through the interlevel insulating film 44.

The fourth embodiment is characterized in that an anti-diffusionconductive film 47 made of a titanium nitride film, for example, isdeposited so as to fill in only the lower part inside thelower-electrode contact hole 45 and the lower part inside theupper-electrode contact hole 46.

Metal interconnections 48, each consisting of a titanium film 48 a, afirst titanium nitride film 48 b, an aluminum film 48 c and a secondtitanium nitride film 48 d, are formed to cover the interlevelinsulating film 44 as well as the inner surfaces of the lower-electrodecontact hole 45 and the upper-electrode contact hole 46. In thisembodiment, one of the metal interconnections 48 is electricallyconnected to the lower electrode 41 via the anti-diffusion conductivefilm 47 inside the lower-electrode contact hole 45. The other metalinterconnection 48 is electrically connected to the upper electrode 43via the anti-diffusion conductive film 47 inside the upper-electrodecontact hole 46.

Hereinafter, a method for fabricating the semiconductor device in thefourth embodiment of the present invention will be described withreference to FIGS. 11(a) through 11(c) and FIGS. 12(a) through 12(c).

First, as shown in FIG. 11(a), the first platinum film 41A and theferroelectric film 42A are sequentially stacked over the entire surfaceof the semiconductor substrate 40.

Thereafter, as shown in FIG. 11(b), the ferroelectric film 42A and thefirst platinum film 41A are selectively etched, thereby forming thecapacitive insulating film 42 out of the ferroelectric film 42A and thelower electrode 41 out of the first platinum film 41A. Then, thecapacitive insulating film 42 is selectively etched in order to form aregion from which a metal interconnection to be electrically connectedto the lower electrode 41 is extended upward. Subsequently, in order torecover and stabilize the crystal structure of the ferroelectric filmconstituting the capacitive insulating film 42, the capacitiveinsulating film 42 is subjected to a heat treatment within oxygenambient.

Next, as shown in FIG. 11(c), the interlevel insulating film 44 isdeposited over the entire surface of the semiconductor substrate 40. Anda first resist pattern 49, having openings over the respective regionswhere the lower-electrode contact hole and the upper-electrode contacthole are to be formed, is formed over the interlevel insulating film 44.Thereafter, the interlevel insulating film 44 is patterned by using thefirst resist pattern 49 as an etching mask, thereby forming thelower-electrode contact hole 45 and the upper-electrode contact hole 46through the interlevel insulating film 44.

Then, the interlevel insulating film 44 is patterned by using the resistpattern 49 as an etching mask, thereby forming the lower-electrodecontact hole 45 and the upper-electrode contact hole 46 through theinterlevel insulating film 44. Thereafter, the second platinum film 43Aand the titanium nitride film 47A are sequentially deposited to coverthe entire surface including the inner surfaces of the lower-electrodecontact hole 45 and the upper-electrode contact hole 46.

Next, the resist pattern 49 is removed and the second platinum film 43Aand the titanium nitride film 47A deposited on the resist pattern 49 arelifted off, thereby leaving the second platinum film 43A inside thelower-electrode contact hole 45 and forming the anti-diffusionconductive film 47 out of the titanium nitride film 47A thereon. Also,inside the upper-electrode contact hole 46, the upper electrode 43 isformed out of the second platinum film 43A and the anti-diffusionconductive film 47 is formed out of the titanium nitride film 47A. Next,as shown in FIG. 12(a), a second resist pattern 50 is formed on thetitanium nitride film 47A in the opening corresponding to the upperelectrode contact hole 46. Next, as shown in FIG. 12(b), after removingthe second platinum film 43A and the titanium nitride film 47 inside thelower electrode contact hole 45 and the second resist pattern 50, thesecond platinum film 43A and the titanium nitride 47 inside the upperelectrode contact hole 46 are remained.

Then, as shown in FIG. 12(c), the metal interconnections 48, eachconsisting of the titanium film 48 a, the first titanium nitride film 48b, the aluminum film 48 c and the second titanium nitride film 48 d, areformed over the anti-diffusion conductive film 47 and the interlevelinsulating film 44. Next, in order to further improve the adhesionbetween the titanium film 48 a constituting the metal interconnections48 and the interlevel insulating film 44, the metal interconnections 48are subjected to a heat treatment.

In the fourth embodiment, the anti-diffusion conductive film 47 made ofthe titanium nitride film 47A including no grain boundaries and having adense structure is formed inside the upper-electrode contact hole 46.Thus, the titanium atoms in the titanium film 48 a constituting themetal interconnections 48 do not pass through the anti-diffusionconductive film 47. Accordingly, during the heat treatment conducted onthe metal interconnections 48, it is possible to prevent the titaniumatoms in the titanium film 48 a from passing through the grainboundaries of metal crystals composing the upper electrode 43 anddiffusing into the capacitive insulating film 42. As a result, in thefourth embodiment, a semiconductor device including a highly reliablecapacitor device can be formed.

Hereinafter, the evaluation of the semiconductor device of the fourthembodiment will be described.

Table 4 shows in comparison the characteristics of the capacitor devicein the semiconductor device of the fourth embodiment and thecharacteristics of a capacitor device in a conventional semiconductordevice.

TABLE 4 Data retention time Breakdown voltage (V) (years) FourthEmbodiment 40 10 Conventional Capacitor 20 1

As can be understood from Table 4, in the fourth embodiment, thebreakdown voltage of the capacitor device is 40 V, which is twice ashigh, as that of the conventional capacitor device. The data retentiontime of the capacitor device of the fourth embodiment is 10 years, whichis ten times as long as that of the conventional capacitor device.

In the foregoing first to fourth embodiments, a titanium nitride film isused as the anti-diffusion conductive film 17, 27, 37, 47.Alternatively, a metal film made of at least one element selected fromthe group consisting of tungsten, iridium, tantalum, rhodium, palladium,zirconium, niobium and vanadium; a metal nitride film made of at leastone element selected from the group consisting of tungsten, tantalum,zirconium, niobium and vanadium; or a metal oxide film made of at leastone element selected from the group consisting of iridium, rhodium,palladium, osmium and ruthenium may be used instead. Since these metalfilms, metal nitride films and metal oxide films include no grainboundaries and have a dense structure, these films also prevent thepassage of titanium atoms in the titanium film composing the metalinter-connections 18, 28, 38, 48, in the same way as the titaniumnitride film.

If one of the above-enumerated metal oxide film is used as theanti-diffusion conductive film 17, 27, 37, 47, then the conductivity ofthe metal oxide film is not damaged even when a heat treatment isconducted within oxygen ambient in order to recover and stabilize thecrystal structure of the ferroelectric film constituting the capacitiveinsulating film 12, 22, 32, 42. This is because the metal oxide film hasconductivity in the state of an oxide.

Also, a multi-layer structure including at least two types of filmsselected from the metal films, the metal nitride films and the metaloxide films may be used as the anti-diffusion conductive film 17, 27,37, 47.

In the first to fourth embodiments, a multi-layer film including aplatinum film and an iridium oxide film, instead of the platinum film,may be used as the lower electrode 11, 21, 31, 41 and/or the upperelectrode 13, 23, 33, 43.

In the third and fourth embodiments, a plurality of upper electrodes 33,43 and a plurality of anti-diffusion conductive films 37, 47, eachhaving a small thickness, may be alternately stacked. In such anembodiment, a stable upper electrode, which is very less likely to bedeformed because of thermal expansion, can be formed.

In the first to fourth embodiments, a perovskite ferroelectric film madeof barium titanate, lead titanate zirconate or the like, or a bismuthlayer shaped perovskite ferroelectric film made of SrBi₂Ta₂O₉ or thelike may be used as the ferroelectric film constituting the capacitiveinsulating film 12, 22, 32, 42.

Also, if an insulating metal oxide film, such as a high dielectric film,other than the ferroelectric film is used as the capacitive insulatingfilm 12, 22, 32, 42, then the capacitor device may be applied to adynamic RAM.

In the first to fourth embodiments, a silicon nitride film or a siliconoxynitride film, instead of the silicon oxide film, may be used as theinterlevel insulating film 14, 24, 34, 44. The semiconductor substrate10, 20, 30, 40 may be an insulating substrate (such as a glasssubstrate), a conductive substrate or a semiconductor substrate on whichtransistors or the like are formed.

What is claimed is:
 1. A method for fabricating a semiconductor device,comprising the steps of: forming a capacitor device including acapacitive lower electrode, a capacitive insulating film made of aninsulating metal oxide film and a capacitive upper electrode on asubstrate; forming an interlevel insulating film, having a contact holereaching the capacitive upper electrode, over the capacitor device;depositing a conductive film preventing the passage of titanium atomstherethrough so as to cover the entire surface of the interlevelinsulating film as well as the contact hole; patterning the conductivefilm such that at least a part of the conductive film located inside thecontact hole is left, thereby forming an anti-diffusion film out of theconductive film; and forming, on the interlevel insulating film, a metalinterconnection including a titanium film such that the metalinterconnection is electrically connected to the capacitive upperelectrode via the anti-diffusion film.
 2. The method for fabricating asemiconductor device of claim 1, wherein the conductive film is a metalnitride film or metal oxide film having conductivity.
 3. The method forfabricating a semiconductor device of claim 1, wherein the capacitiveinsulating film is a ferroelectric film or a high dielectric film. 4.The method for fabricating a semiconductor device of claim 1, whereinthe titanium film is an adhesive layer, formed as a lowermost layer ofthe metal interconnection, for improving adhesion between the metalinterconnection and the capacitive upper electrode, and wherein theanti-diffusion film is a titanium nitride film.
 5. The method forfabricating a semiconductor device of claim 1, wherein the capacitiveupper electrode has a crystal structure including a grain boundary.